1. Technical Field
The present technology relates to a tire puncture sealant and more specifically relates to a tire puncture sealant including a natural rubber and a surfactant.
2. Related Art
Automobile manufacturers are more frequently providing puncture repair kits as standard or optional equipment. Such puncture repair kits contain a tire puncture sealant as an essential constituent and can also include a compressor as an optional constituent. Actual products are generally compact packages that combine the tire puncture sealant, known as an “emergency tire puncture repairing agent” or the like, and a low capacity compressor that draws power via a cigarette lighter socket.
Japanese Patent No. 3751729 describes a puncture sealant for sealing an inner-cavity surface of a tire formed from a deproteinized rubber latex produced by removing protein contained in rubber particles in crude rubber from a natural rubber latex. Moreover, the puncture sealant is described as including a nitrogen content of 0.1 wt % or less and an ammonia content of 0.5 wt % or less but 0.1 wt % or greater per a rubber solid content of the deproteinized rubber latex, which can enhance the sealing effect while maintaining superior decomposition resistance and liquefaction stability, and, moreover, can prevent corrosion damage to steel cords and irritating odor caused by ammonia (paragraphs 0010 and 0047). This puncture sealant preferably includes from 0.01 to 1.8 wt % of a surfactant per the rubber solid content of the deproteinized rubber latex as a stabilizer (paragraph 0012). Examples of the stabilizer that can be used include carboxylic acids, sulfonic acids, sulfate esters, phosphoric acid esters, or similar anionic surfactants; and/or polyoxyalkylene ethers, polyoxyalkylene esters, polyhydroxy alcohol fatty esters, sucrose fatty acid esters, alkylpolyglycosides, or similar nonionic surfactants. Furthermore, among carboxylic acid anionic surfactants, fatty acid salts and rosinate salts are preferable, and among polyoxyalkylene ether nonionic surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene lauryl ether sodium sulfates (Emal E-70C, manufactured by Kao Corporation), and the like are preferable (paragraph 0033). Additionally, it is described that using potassium rosinate as the stabilizer is preferable for the purposes of initiating the crosslinking of the rubber particles in the latex via stimulation such as pressure or the like, heightening of solidification and coagulation properties, which are pressure-sensitive properties, and enhancing sealability (paragraph 0012).
Japanese Patent No. 4109435 describes a puncture sealant for sealing an inner-cavity surface of a tire formed from a deproteinized rubber latex produced by removing protein contained in rubber particles in crude rubber from a natural rubber latex; and including a tackifier, an antifreezing agent, and a surfactant; wherein the puncture sealant is described as including a nitrogen content of 0.1 wt % or less and an ammonia content of 0.5 wt % or less per a rubber solid content of the deproteinized rubber latex. One or more of ethylene glycol and propylene glycol is used as the antifreezing agent, and, moreover, this glycol constitutes more than 25 wt % and 35 wt % or less per a gross weight of the puncture sealant. Additionally, the surfactant is a mixture including ammonium laurate or triethanolamine laurate and a fatty acid salt having a carbon number of 9 to 18. Thereby, a puncture sealant for tires is described in which storage performance can be enhanced and solidification of the rubber component while in storage that leads to injectability and sealability being hindered can be prevented (paragraphs 0008 and 0028). Additionally, it is described that ammonium laurate and triethanolamine laurate can be more preferably used because they display particularly superior coagulation suppressing effects, and, moreover, have properties that make possible the enhancement of said coagulation suppressing effects proportional to a content thereof (paragraph 0019).
Japanese Unexamined Patent Application Publication No. 2006-111726 describes a puncture sealant for sealing a hole of a punctured tire. This puncture sealant includes a natural rubber latex and a antifreeze liquid, and further includes a resin-based emulsion. It is described that the sealing speed of a puncture hole is fast and that the puncture sealant has long term stability (paragraphs 0005 and 0007). Additionally, it is described that in the resin-based emulsion, a nonionic surfactant is used for the emulsifier; and at least one selected from a modified phenolic resin, a petroleum resin, and a carboxylic acid modified terpene resin is used for the resin component (paragraph 0006). Moreover, it is also described that the long term stability of the puncture sealant can be enhanced because the free nonionic surfactant included in the resin-based emulsion stabilizes an entirety of the puncture sealant (paragraph 0008).
Japanese Unexamined Patent Application Publication No. 2006-152239 describes an excellent puncture sealant including at least one synthetic rubber latex selected from the group consisting of SBR latex, NBR latex, MBR latex, carboxyl modified NBR latex, and carboxyl modified SBR latex; having a gelling factor measured by an automatic maron mechanical stability tester in compliance with JIS K 6387 of from 0.001 to 10%, and having superior storability and puncture hole sealability (paragraphs 0012 and 0019). Additionally, it is described that this puncture sealant preferably includes a resin-based emulsion in order to enhance sealability, and that the resin-based emulsion preferably uses a nonionic surfactant as an emulsifier from the perspective of stability. If an anionic surfactant and/or a cationic surfactant is used as the main emulsifier, the puncture sealant will destabilize and the emulsion will break down as a result of mixing with an antifreezing agent (paragraph 0029).
Tire puncture sealants like those described above are typically introduced into a tire from an air filling part of the tire. After the tire is filled with air to a specified air pressure, the tire puncture sealant reaches a puncture hole via the running of the vehicle. Moreover, aggregates of rubber particles form due to compressive forces and shear forces exerted on the tire as it contacts the ground and rotates, thereby sealing the puncture holes.
Recently, it is said that that tires that are in use are generally punctured at a rate of once per year. Therefore, the frequency at which a sealing agent is actually used is relatively low. Therefore, while tire puncture sealants must have superior sealability, they must also have the ability to endure storage in a vehicle for an extended period of time.